Power plant using organic working fluids

ABSTRACT

A closed Rankine cycle power plant using an organic working fluid includes a solar trough collector for heating an organic working fluid, a flash vaporizer for vaporizing the heated organic working fluid, a turbine receiving and expanding the vaporized organic working fluid for producing power or electricity, a condenser for condensing the expanded organic working fluid and a pump for circulating the condensed organic working fluid to the solar trough collector. Heated organic working fluid in the flash vaporizer that is not vaporized is returned to the solar trough collector.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 11/754,628, filed onMay 29, 2007, the entire contents of which are incorporated herein byreference. U.S. application Ser. No. 11/754,628 is a continuation ofU.S. application Ser. No. 11/067,710, filed on Mar. 1, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to organic fluids, and more particularlyto organic fluids for use as the working fluid in high-temperatureOrganic Rankine Cycle (ORC) applications and as the heat transfer fluidin heat transfer cycles for a range of low and high temperatures, and apower plant using such organic fluids.

2. Background

High-temperature organic working fluids have been introduced as theworking fluids in power plants and as working; and heat transferintermediates in order to overcome the shortcomings of the use of thewater steam medium used for heat transfer or for waste heat recovery andpower generation. Heat-energy converters, based on the thermodynamicOrganic Rankine Cycle, or similar beat-energy transfer systems, areuseful in heat recovery and power generation in particular in remotelocations, where the heat is derived from various sources, such as gasturbine exhaust gases, combustion of conventional fuels, combustion ofbiomass fuels, geothermal sources, solar heat collects and waste heat inpower plants and other industrial processes, for the purpose ofproducing electrical power in the range of from a hundred or mace Watts(W) and up to a few of tens Megawatts (MW). Organic fluids sustainableat temperatures as high as about 350° C. are advantageous overwater-steam, and can be successfully utilized in power generation cycleseven at low condensing temperatures and high turbine expansion ratioswhere the use of steam may be limited due to formation of liquiddroplets at the turbine outlet due to the expansion of the steam whichmay cause erosion to the turbine blades. Because of the nature of theorganic fluids they become superheated (or dry) in the expansion processa characteristic which prevents the formation of liquid droplets as isthe case with steam. Organic fluids and their derivatives operable undera range of relatively low temperatures normally up to about 20000 areCFCs, Freon, butane including n-butane and iso-butane, and pentane, alsoincluding the n-pentane and iso-pentane isomers. For applications wherehigher operating temperatures are required a transition was required toaromatic hydrocarbons, alkylated aromatic hydrocarbons, fluorinatedhydrocarbons such as F75 and F43 and silicone based oils. Examples foralkylated aromatic hydrocarbons are commercial Dowtherm J, which is amixture of isomers of alkylated aromatic hydrocarbon manufactured by theDow Chemical Company and Therminol LT, an alkyl substituted aromatichydrocarbon, manufactured by the Solutia Inc.

SUMMARY OF THE INVENTION

According to a feature of the invention, a closed Rankine cycle powerplant using an organic working fluid includes a solar trough collectorfor heating an organic working fluid, a flash vaporizer for vaporizingthe heated organic working fluid, a turbine receiving and expanding thevaporized organic working fluid for producing power or electricity, acondenser for condensing the expanded organic working fluid and a pumpfor circulating the condensed organic working fluid to the solar troughcollector.

According to another feature of the invention, heated organic workingfluid in the flash vaporizer that is not vaporized is returned to thesolar trough collector.

BRIEF DESCRIPTION OF THE DRAWINGS

A description of the present inventive subject matter includingembodiments thereof is presented and with reference to the accompanyingdrawings, the description not meaning to be considered limiting in anymanner, wherein:

FIG. 1 shows an embodiment of a power plant in which the working fluidsof the present invention can be used;

FIG. 2 shows a further embodiment of a power plant in which the workingfluids of the present invention can also be used; and

FIG. 3 shows an embodiment of a portion of a power plant in which theworking fluids of the present invention can be used.

DETAILED DESCRIPTION

According to the present invention, an improved, commercially availableorganic working fluid is provided, which is operable under a broad rangeof temperatures, is thermally stable, has high critical temperature, lowfreezing or solidification temperature and has a high auto-ignitiontemperature. Such an organic working fluid is useful in Organic RankineCycle (ORC) power plants or units and other systems of the like; as anintermediate fluid for heat-recovery, wherein heat from various heatsources is transferred using the intermediate fluid to a further workingfluid and converted into work, and the intermediate fluid is alsoexploited to produce electricity. Such working fluids are also operableas heat transfer fluids either in ORC power plants or units or in otherheat transfer systems.

For this purpose the present invention presents a working fluidcomprising at least one highly branched, heavy iso-paraffin hydrocarbon,or a mixture of two or more of such hydrocarbons. Preferably at leastone highly branched iso-parafin hydrocarbon is present as the majorcomponent (i.e. at least 50% by volume) in the working fluid. The highthermal stability of such hydrocarbons is provided due to the locationof the methyl radical (CH₃) arranged to achieve highly stable compounds.Such highly branched heavy iso-paraffin hydrocarbons or organic fluidshave high boiling point temperatures as well as high auto-ignitiontemperatures, and low freezing point temperatures. They exhibit highthermal stability, and in addition are benign to the environment, andsafe for human use. Another advantage is their commercial availability,enabling, through their use, cost effective electricity or powerproduction from various heat sources, or heat transfer in power plantsor in other uses.

U.S. Pat. No. 5,612,888 discloses, inter alia, the use of isoparaffinsas non-Newtonian liquid bearing materials as support for head componentsof a head-disk assembly over rigid disks. Such application of liquid isoparaffins is confined to a narrow temperature range set by thetemperature operation limits of the disk drives, which may be forexample between 5° C. and 55° C.

A preferred sub-class of the class of the branched iso-paraffins whichare suitable to be incorporated in organic working fluids of the presentinvention includes 8 to 20 carbon atom-containing hydrocarbons having atleast one methyl radical (CH₃) arranged to achieve a highly stablecompound. Preferably, the branched iso-paraffins are highly branched,meaning that they have 8-20 methyl groups attached to tertiary orquaternary carbon atoms. As used herein, “substantially branched” meansat least 8 branched (i.e. non-end groups) methyl groups. Suchiso-paraffins, or a mixture of two or more or them, are used accordingto the present invention as the major component in working fluids inpower plants operating according to an Organic Rankine Cycle (ORC), orin any other high temperature heat recovery system, or as thermal fluidsin heat transfer cycles.

Preferred operating temperatures of the working fluids in the powerplant or heat transfer cycle are in the range of about −50° C. up toabout 350° C. Besides exhibiting thermal stability in this temperaturerange, such a wide range of operating temperatures results in improvedefficiency for the heat recovery in power plants or of heat transfer inheat transfer systems.

The branched iso-paraffins disclosed in the present invention areoptionally modified to acquire fire-retarding characteristics bysubstituting all or some of the methyl groups with one or moresubstitutents, including for example substituents such as halogens,including fluorine, chlorine, and bromine, or halogen containingsubstituents.

Preferred iso-paraffin hydrocarbons of the present invention are thecompounds according to formula (I):C_(n)H_(2n+2)  (I)where n is between 8 and 20.

The working fluids of the present invention may comprise in additionconventional additives, where such additives may be selected fromfire-retardant agents, flow aids, corrosion inhibitors, lubricants,anti-freezing agents, antioxidants, and process oils and mixturesthereof.

In one preferred embodiment of the present invention the branchediso-paraffin organic working fluid is, or comprises, iso-dodecane or2,2,4,6,6-pentamethylheptane.

In a second preferred embodiment of the present invention the branchediso-paraffin organic working fluid is, or comprises, iso-eicosane or2,2,4,4,6,6,8,10,10-nonamethylundecane.

In a third preferred embodiment of the present invention the branchediso-paraffin organic working fluid is iso-hexadecane or2,2,4,4,6,8,8-heptamethylnonane.

In a fourth preferred embodiment of the present invention the branchediso-paraffin organic working fluid is isooctane or 2,2,4trimethylpentane.

In a fifth preferred embodiment of the present invention the branchediso-paraffin organic working fluid is iso-nonane or 2,2,4,4tetramethylpentans.

All of the compounds disclosed herein above are useful as majorcomponents in organic working fluids in power plants employing theRankine cycle or similar systems for heat or waste heat recovery, or inheat transfer cycles, and are thermally stable in a wide temperaturerange of abut −50° C. up to about 350° C.

Non-limitative examples of energy recoveries or heat transfer systemsand methods of producing power therefrom, that may employ the organiciso-paraffin fluids of the present invention, are referred to below:

As an example of an embodiment of a system in which the presentinvention can be used reference is now made to FIG. 1, and referencenumeral 10 designates an embodiment of apparatus for producing power inaccordance with the present invention. As can be seen from the drawing,the apparatus comprises intermediate fluid heater/vaporizer 12 by whichvaporized intermediate fluid is produced using heat from heat source 13e.g. using heat contained in hot gases, etc. The vaporized intermediatefluid is supplied to organic working fluid vaporizer 22 where it iscondensed by transferring heat to organic fluid present in the vaporizerso that vaporized organic fluid is produced. Intermediate fluidcondensate produced is returned to intermediate fluid heater/vaporizer12 using pump 19. The vaporized organic fluid is supplied to organicvapor turbine 24 wherein it expands and produces power. Preferably,generator 26 is driven by organic vapor turbine 24 and produceselectricity. Expanded vaporized organic fluid exiting organic vaporturbine 24 is supplied to organic fluid condenser 28 and organic fluidcondensate is produced. Pump 30 supplies organic fluid condensateexiting organic fluid condenser 28 to organic working fluid vaporizer22. In accordance with the present invention, prior to supplyingvaporized intermediate fluid exiting intermediate fluid vaporizer 12 toorganic working fluid vaporizer 22, the vaporized intermediate fluid issupplied to intermediate fluid turbine 16 wherein the vaporizedintermediate fluid expands and produces power. Also here, preferably,intermediate fluid turbine 16 drives generator 18 that produceselectricity.

In operation, intermediate fluid present in intermediate fluid vaporizer12 extracts heat from heat source 13 e.g. hot gases and intermediatefluid vapor is produced. The intermediate fluid vapor is suppliedpreferably to intermediate fluid turbine 16 and expands thereinproducing power and expanded intermediate fluid vapor exits intermediatefluid turbine 16. Since preferably, generator 18 is coupled tointermediate fluid turbine 16 electricity is produced. Expandedintermediate fluid vapor exiting intermediate fluid turbine 16 issupplied via line or conduit 20 to organic working fluid vaporizer 22.Organic working fluid present in organic working fluid vaporizer 22extracts heat from the expanded intermediate fluid vapor andintermediate fluid condensate as well as vaporized organic working fluidis produced. Intermediate fluid condensate is supplied using pump 19 tointermediate fluid vaporizer 12. Vaporized organic working fluid issupplied to organic working fluid turbine 24 wherein it expands andpower is produced. Expanded organic working fluid vapor exits organicworking fluid turbine 24. Preferably, organic working fluid turbine 24is coupled to generator 26 and electricity is produced. The expandedorganic working fluid vapor is supplied to organic working fluidcondenser 28 that is preferably air-cooled and organic working fluidcondensate is produced. Pump 30 supplies organic working fluidcondensate to organic working fluid vaporizer 22.

The intermediate fluid mentioned in the embodiment described above canbe the organic working fluids of the present invention disclosed herein.The preferred intermediate fluid is advantageous since their use avoidsproblems of freezing, operates without being at vacuum conditions andthere is no need for chemical treatment and blow down as is usually thecase with water when used as an intermediate fluid. Preferably, theintermediate fluid is useful in a relative high temperature range:vaporizing temperature between about 250° C. and about 315° C. At thesetemperatures, the pressure of the intermediate fluid is between about 9kPa and 2600 kPa. The relatively low pressures mentioned above make thistype of fluid particularly suitable for use in the present invention.Often, the condensing temperature of the intermediate fluid on theintermediate fluid side of organic working fluid vaporizer 22 willpreferably be in the range of about 200° C. to about 120° C. but can bemuch lower if need be. Furthermore, the use of this type of intermediatefluid as a heat transfer medium for transferring heat from the heatsource to the organic working fluid and as well as producing power fromthe intermediate fluid increases the efficiency of the power producingsystem on a whole. Preferably, the organic working fluid comprisespentane, either n-pentane or iso-pentane, n-butane, iso-butane as wellas additional fluids such as hydrocarbons, for example aliphaticparaffins in their normal and isomeric form.

Furthermore, if preferred organic fluid power cycle I can include apre-heater, superheater and recuperator. In addition, if preferred,generators 18 and 26 can be replaced by a single common generator drivenby turbines 16 and 24 either using dual shaft ends in the single commongenerator or through a gear drive. Most preferred, the common generatoris interposed between turbines 16 and 24.

Referring now to FIG. 2, numeral 10A refers to a further embodiment ofan example of a system or cycle in which the organic working fluid ofthe present invention is used and which includes, as shown, arecuperator in the intermediate fluid. As can be seen from the figure,intermediate fluid vapor produced by intermediate vaporizer 12A presentin heat recovery vapor generator 40A is supplied to vapor turbine 16Afor producing power or electricity using generator 18A. Numeral 21Edesignates an intermediate fluid recuperator in which heat istransferred from expanded intermediate fluid vapor exiting intermediatefluid turbine 16A to intermediate fluid condensate supplied by pump 19Afrom the intermediate fluid side of organic working fluid vaporizer 22A.In this embodiment, portion of the intermediate fluid condensate exitingthe intermediate fluid side of organic working fluid vaporizer 22A issupplied to organic fluid pre-heater 23A for pre-heating the organicworking fluid prior to supplying it to organic working fluid pre-heater25A. In this way, heat from heat source 13A is added to the intermediatefluid condensate exiting organic pre-heater 23A. A further portion ofthe intermediate fluid condensate exiting the intermediate fluid side oforganic working fluid vaporizer 22A is supplied to intermediate fluidrecuperator 21E. In addition, in this embodiment organic working fluidrecuperator 27E is included and is used for transferring heat fromexpanded organic working fluid vapor exiting organic working fluidturbine 24A to organic working fluid condensate supplied by pump 30Afrom organic working fluid condenser 28A. Heated organic working fluidcondensate exiting organic working fluid recuperator 27E is supplied toorganic working fluid pre-heater 28A. Apart from these items previouslymentioned with reference to the present embodiment described withrelation to FIG. 2, this embodiment is similar to the embodimentdescribed with relation to FIG. 1 and also operates in a similar manner.

In certain circumstances, all of the intermediate fluid exiting theintermediate fluid side of the organic working fluid vaporizer 22A canbe supplied to organic working fluid pre-heater 23A. Thereafter, thecooled intermediate fluid exiting to organic working fluid pre-heater23A can be supplied to heat source 13A the heated intermediate fluidexiting heat source 13A being supplied to intermediate fluid recuperator21A.

In FIG. 2, generator 18A is preferably shared by the output ofintermediate turbine 16A and organic working fluid turbine 24A. This isbecause intermediate turbine 16A can operate efficiently at relativelylow rotational speeds (1500-1800 RPM, permitting it to be directlycoupled to generator 18A whose rotational speed also is relatively low(1500-1800 RPM). Similarly, the rotational speed of organic workingfluid turbine 24A can also be relatively low (1500-1800 RPM, permittingit also to be directly coupled to generator 18E. Thus generator 18A isinterposed between intermediate turbine 16A and organic working fluidturbine 24A. However, if preferred, separate generators can be provided.

Furthermore, preferably, the embodiment described with reference to FIG.2 comprises two separate entities, heat source unit or heat recoveryvapor generator 40A and power cycle unit 50A.

As mentioned above, the intermediate fluid of the embodiment shown inFIG. 2 can be the organic working of the present invention.

It is to be pointed out that the intermediate fluid specified above canbe used for all the embodiments mentioned herein.

Examples of heat sources from which the present invention can extractheat from are waste heat from gas turbines, waste heat from otherindustrial processes, waste heat produced in cement manufacture and inthe cement manufacturing industry, heat produced by the combustion ofconventional fuels, heat produced by the combustion of biomass fuel,geothermal resources including geothermal steam and geothermal liquid,solar energy, etc. In addition, the present invention can be used e.g.for producing electrical power in the range of from about a hundred ormore Watts (W) up to a few tens of Megawatts (M %)

Furthermore, while this specification refers to the heat transfer cycleas using an intermediate fluid, it is possible to consider, inaccordance with the present invention, the cycle using the intermediatefluid, when referring to power production, as a topping cycle with theorganic working fluid cycle as a bottoming cycle,

Moreover, while the embodiments of the present invention describe theuse of generators 18 and 26 or the use of a common generator forproducing electricity, in accordance with the present invention, thepower produced by turbines 16 and 24 or either of them can be used asmechanical power. Thus, for example, they can run a compressor, otherloads, etc.

Also in this embodiment, the intermediate fluid can be the organicworking fluids of the present invention disclosed herein.

Furthermore, it is to be pointed out that while the intermediate fluidspecified above is described as operating in a cycle wherein theintermediate fluid transfers heat from the heat source to a furtherorganic working fluid, the organic working fluid of the presentinvention can be used in accordance with the present invention in such apower cycle wherein the intermediate fluid is used in a power cyclewithout transferring heat to a further organic working fluid.

In a further preferred embodiment of the present invention, the organicworking fluids of the present invention may be used for producing poweror electricity from a heat source such as solar energy wherein theorganic fluids disclosed in the present invention may be used in a powerplant operating according to the organic Rankine cycle (see FIG. 3). Insuch a case, these organic working fluids are heated preferably in solarcollector 40B such as a solar trough collector 42B and then supplied toa flash chamber, tank or vaporizer 44B for producing organic vapor whichis supplied to a vapor turbine of an organic Rankine cycle (ORC) powerplant for producing power or electricity. Liquid working fluid from theflash tank that is not flashed is recycled to solar collector 40B eitherto the inlet of a single solar collector (not shown) or to the inlet ofthe second solar collector of the pair of serially connected solarcollectors 42B which heat the organic fluids flowing sequentiallythrough the two solar collectors 42B. Thereafter, the expanded organicworking fluid is condensed in a condenser and the organic working fluidcondensate is returned from the organic Rankine cycle (ORC) power plantto the solar collector.

Further non-limitative examples of energy or heat recovering or heattransfer systems and methods of producing power therefrom, that mayemploy the organic iso-paraffin fluids of the present invention,disclosed in several former publications, are all incorporated herein byreference.

In one preferred embodiment of the present invention the organiciso-paraffin fluids may be employed in vapor turbines and in a methodfor the operation of vapor turbines thereof; applying a heat recuperatorin ORC power plants or units, as disclosed in U.S. Pat. No. 8,040,528.

In a second preferred embodiment of the present invention the sameorganic fluids may be employed in power plants applying cascaded vaporturbines and in a method thereof as disclosed in EP 1174 590 preferablyusing the same organic fluid as the intermediate fluid. In such systemsand methods thereof a vaporized intermediate, as for example an organic,alkylated heat transfer fluid, preferably a synthetic alkylated aromaticheat transfer fluid, is used as the primary recipient of heat from theheat source, transferring it afterwards to the organic fluid.

In a third preferred embodiment of the present invention., as disclosedin U.S. Pat. No. 4,760,705, the organic fluids of the present inventionmay be employed as the working fluid or intermediate working fluid inRankine cycle power plant disclosed therein wherein in this patent animproved working fluid useful in power plants selected from the groupconsisting bicyclic aromatic hydrocarbons, substituted bicyclic aromatichydrocarbons, heterocyclic bicyclic aromatic hydrocarbons, substitutedheterocyclic bicyclic aromatic hydrocarbons, bicyclic or heterocycliccompounds where one ring is aromatic and the other condensed ring isnon-aromatic, and their mixtures are disclosed. In a further aspect ofthis US, patent a binary Rankine cycle power plant is provided in whichthe condenser of the high temperature and pressure turbine is cooled bya different working fluid which is vaporized thereby and supplied to alow temperature and turbine.

In a fourth preferred embodiment of the present invention, as disclosedin U.S. Pat. No. 6,701,712, the organic fluids of the present inventionmay be employed in a method and apparatus of producing power whereinheat received from a hot-air clinker process in cement factories istransferred to a heat transfer fluid, e.g. thermal oil in an air-heattransfer fluid heat-exchanger and the heat is used to vaporize organicfluid in a vaporizer for power production using the vaporized workingfluid in a turbine.

In a fifth preferred embodiment of the present invention, the organicfluids of the present invention may be employed in a heat recoverymethod and system thereof according to U.S. Pat. No. 8,671,648, whereinheat emitted from a heat source, such as a gas turbine is transferred toan intermediate fluid, that can be pressurized water, which transfersthe heat to an organic working fluid. Vaporized organic fluid producedthereby is then used to drive an organic fluid turbine for producingpower by using an electric generator connected to the organic fluidturbine.

In a sixth preferred embodiment of the present invention, the organicfluids of the present invention may be employed in a power plantoperating according to gas turbine system disclosed in U.S. Pat. No.5,687,570. According to this system a water-based, closed loop Rankinecycle power plant is included. Also, according to this system, the steamcondenser of the water-based, closed loop Rankine cycle power plant iscooled by organic fluid condensate which is thus pre-heated and thensupplied to the organic fluid vaporizer, the organic fluid vaporproduced thereby operating an organic vapor turbine. In severalembodiments included in this patent, the steam condenser operates as anorganic fluid vaporizer.

In a seventh preferred embodiment of the present invention, the organicfluids of the present invention may be employed in a power plantoperating on steam according to methods of operation and powerproduction thereof disclosed in U.S. Pat. No. 5,497,624. This system andmethod includes apparatus for producing power using geothermal fluidsuch that geothermal steam produces power in a steam turbine, andexpanded geothermal steam vaporizes organic fluid for producingadditional power in a closed organic Rankine cycle turbine bothcontained in each of a plurality of integrated power plant unit modules.Furthermore, means for compressing non-condensable gases present in thesteam condensers contained in each power plant module can be providedsuch that the compressed non-condensable gases can be vented into are-injection well together with pressurized steam condensate produced inthe steam condensers. Moreover, geothermal liquid contained in thegeothermal fluid can be re-injected into the re-injection well.

In an eighth preferred embodiment of the present invention disclosed inU.S. Pat. No. 4,542,625, the organic fluids of the present invention maybe employed in a closed Rankine cycle power plant or unit operatingtogether with a geothermal steam turbine for producing power.

In a ninth preferred embodiment of the present invention, disclosed inU.S. Pat. No. 4,700,549, the organic fluids of the present invention maybe employed in a heat recovery cascaded power plant and a method forproducing power. The power plant integrates a plurality of independentclosed Rankine cycle units operating serially, wherein a law to mediumtemperature source fluid, such as for example an industrial fluid orgeothermal fluid is applied serially to the vaporizer of closed Rankinecycle units producing heat depleted source fluid and the heat depletedsource fluid is applied to all of the pre-heaters in parallel wherein apre-heater is provided for each vaporizer.

In a tenth preferred embodiment of the present invention, disclosed inU.S. Pat. No. 4,578,953, the organic fluids of the present invention maybe employed in serially operating integrated closed Rankine cycle powerplants, having advantageously a better efficiency in heat recovery andpower production. In the serially operating integrated closed Rankinecycle power plants, a low to medium temperature source fluid, such asfor example an industrial fluid or geothermal, fluid is applied seriallyto the vaporizer of closed Rankine cycle units producing heat depletedsource fluid and the heat depleted source fluid is applied to all of thepre-heaters in parallel wherein a pre-heater is provided for eachvaporizer.

In an eleventh preferred embodiment of the present invention, disclosedin U.S. Pat. No. 4,551,980, the organic fluids of the present inventionmay be employed in the hybrid power plant disclosed therein. Such ahybrid system is disclosed in Closed Cycle Vapor Turbogenerator—AReliable Remote Prime Power Source” by N. S. Christopher and J. Gropper,presented at the International Telecommunications Energy Conference inWashington, D.C. October 1982, pages 443-449. The hybrid power plantdisclosed in U.S. Pat. No. 4,551,980 includes an intermittently operablenon-fuel consuming power generator, such as a photovoltaic cell array,or a wind generator, connected through a control-circuit to a batteryfor charging the same during operation of the power generator and forsupplying current to a time-wise, substantially constant, electricalload. In addition, the hybrid power plant includes an electric generatorconnected to an intermittently operable prime mover for charging thebattery and supplying power to the electrical load when, the prime moveris operated. According to this patent, the prime mover can be a Rankinecycle organic fluid vapor turbogenerator or power unit or power plantemploying the Rankine cycle using the organic working fluid including avaporizer and a burner such as that described in U.S. Pat. No. 3,409,782and in “Considerations for evaluating, maintaining pipe line coatings”,Diane Tracey, PIPE LINE & GAS INDUSTRY, August 1997 and “Two Decades ofSecurity Along TranAlaska Pipeline”, Frichtl, W., Pipeline & GasJournal, July, 1997.

In a twelfth preferred embodiment of the present invention, disclosed inU.S. patent application Ser. No. 10/470,800, now U.S. Pat. No.6,981,378, the organic fluids of the present invention may be employedin the Rankine cycle turbine included in the uninterruptible powersupply and the method for supplying uninterruptible power to a loaddisclosed therein. This method for supplying interruptible power to aload connected to a power line comprises connecting the power line to arotatable member comprising a Rankine cycle turbine coupled to devicethat preferably operates as a motor when line power is applied to thedevice thereby rotating the member at a standby rotational speed forstoring a predetermined amount, of kinetic energy in the rotatingmember, and that operates as a generator when line power is inoperative,the member being rotated by the application of vaporized working fluidto the turbine. Additionally, the method includes vaporizing workingfluid and maintaining the same at an operational temperature level onlywhen the line power is inoperable. Furthermore, the method includesholding working fluid at a standby temperature level while the powerline is operative, the standby temperature level preferably beinggreater than the operational temperature level whereby the working fluidcontains a predetermined amount of stored thermal energy while the powerline is operative. In addition, the method includes applying thevaporized working fluid to the turbine thereby rotating the rotatablemember in response to lose of line power whereby the turbine rotates themember at a nominal speed less than the standby rotational speed.Moreover, the method includes connecting the device to the load wherebypower is supplied to the load while the power line is inoperative sothat the stored thermal energy in the working fluid and thepredetermined amount of kinetic energy are converted to power for theload upon loss of line power. The Rankine cycle turbine disclosed inthis US patent application is included in a Rankine cycle turbine systemwhich also includes a boiler, a burner, a condenser, a working fluidsupply to the bearings including a reservoir for lubricating thebearings, and working fluid cycle pump, e.g. a pitot pump.

In addition, it should be noted that means mentioned in thisspecification refer to suitable means for carrying out the presentinvention.

Furthermore, it should be pointed out that the present inventionincludes as well the method for operating the apparatus disclosed withreference to above-described figures.

All the above description has been provided for the purpose ofillustration and is not meant to limit the invention in a way. As willbe apparent to a skilled person, the invention can be carried out byusing different compounds, all without exceeding the scope of theinvention.

All references, patents, applications, tests, standards, documents,publications, brochures, texts, articles, etc. mentioned herein areincorporated by reference. Where a numerical limit or range is stated,the endpoints are included. Also, all values and subranges within anumerical limit or range are specifically included as if explicitlywritten out.

All the above description and examples have been provided for thepurpose of illustration and are not meant to limit the invention in anyway. As will be apparent to a skilled person, the invention can becarried out in using different compounds, all without exceeding thescope of the invention.

The invention claimed is:
 1. A closed Rankine cycle power plant using anorganic working fluid, comprising: first and second solar troughcollectors connected in series for heating an organic working fluidflowing sequentially through the respective first and second solartrough collectors; a flash vaporizer for vaporizing the heated organicworking fluid exited from the first and second solar trough collectors;a turbine receiving and expanding the vaporized organic working fluid,for producing power or electricity; a condenser for condensing theexpanded organic working fluid; and a pump for circulating the condensedorganic working fluid sequentially through the first and second solartrough collectors, wherein the heated organic working fluid in the flashvaporizer that is not vaporized is returned to the second solar troughcollector and not to the first solar trough collector.
 2. A closedorganic Rankine cycle power system for producing power from analternative energy heat source such as solar energy or geothermal fluid,comprising: a) a vaporizer in which liquid organic working fluid isvaporized using heat from said solar energy or geothermal fluid heatsource so that an organic working fluid vapor and a heat depleted solarenergy or geothermal heat source fluid are produced; b) a turbine forexpanding the vaporized organic working fluid and producing power and anexpanded organic working fluid vapor; c) a further vaporizer whereinfurther organic working fluid is vaporized and further organic workingfluid vapor is produced; d) a further turbine for expanding the furtherorganic working fluid vapor and producing power and expanded furtherorganic working fluid vapor: e) a conduit for supplying organic workingfluid condensate to a preheater for preheating said working fluidcondensate using heat from said heat depleted solar energy source fluidor said heat depleted geothermal fluid and producing preheated organicworking fluid condensate; f) a condenser to which the expanded furtherorganic working fluid vapor is supplied, said condenser producingfurther organic working fluid condensate; g) means for supplying saidfurther organic working fluid condensate to said further vaporizer; andh) a further preheater for preheating said further organic working fluidcondensate prior to supplying it to said further vaporizer.
 3. Thesystem according to claim 2, wherein said further vaporizer comprises acondenser/vaporizer to which said expanded organic working fluid vaporis also supplied so that said expanded fluid vapor transfers heat tosaid further organic working fluid, producing said further organicworking fluid vapor as well as organic working fluid condensate.
 4. Thesystem according to claim 2, further comprising means for supplying saidfurther working fluid condensate to said further preheater.
 5. Thesystem according to claim 2, further comprising a valve controlling theamount of working fluid condensate supplied to said further preheater.6. The system according to claim 2, further comprising a recuperator fortransferring heat to said working fluid condensate, from said expandedworking fluid vapor received therein, and producing heated working fluidcondensate.
 7. The system according to claim 3, further comprising arecuperator for receiving expanded working fluid vapor prior tosupplying the expanded working fluid vapor to the condenser/vaporizerand transferring heat to working fluid condensate and producing heatedworking fluid condensate.
 8. The system according to claim 6, furthercomprising means for supplying the heated working fluid condensateexiting said recuperator to said vaporizer.
 9. The system according toclaim 6, further comprising means for supplying said working fluidcondensate to said recuperator.
 10. The system according to claim 2,further comprising means for dividing the flow of the working fluidcondensate and controlling the amount of working fluid condensatesupplied to said further preheater.
 11. The system according to claim 2,wherein said vaporizer comprises a solar collector.
 12. The systemaccording to claim 11, wherein said vaporizer further comprises a flashvaporizer.
 13. The system according to claim 12, further comprising afurther solar collector for heating working fluid recycled from saidflash vaporizer.
 14. The system according to claim 2, wherein saidvaporizer comprises two solar collectors.
 15. The system according toclaim 14, wherein said two solar collectors are connected serially. 16.A system according to claim 2, wherein said organic working fluidcomprises an iso-paraffin selected from the group consisting ofiso-dodecane or 2,2,4,6,6-pentamethylheptane, iso-eicosane or2,2,4,4,6,6,8,10,10 nonamethylundecane, iso-hexadecane or2,2,4,4,6,8,8-heptamethylnonane, isononane or 2,2,4,4 tetramethylpentaneand a mixture of two or more of said compounds.
 17. The system accordingto claim 2, wherein said geothermal fluid comprises geothermal steam.18. The system according to claim 2, wherein said geothermal fluidcomprises geothermal liquid.